Method of bending metal strips edgewise.



GEWISE.

APPLICATION FILED NOV. 28. 1906. 91 8,425. Patented Apr. 13. 1909.

6 SHEETS-SHEET 1.

Inventor. Gan/J ,51 Damn,

L 5/%V-v AZLU QEU Witnes 5 es W7KM G. S. DUNN.

METHOD OF BENDING METAL STRIPS EDGEWISE.

APPLICATION FILED NOV. 28, 1906.

9 1 8,425 Patented Apr. 13, 1909.

6 SHEETSSHEET 2.

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Gama 5. Dunn,

Invento F, 113120 5. Dunn,

Witne 5 585: W%64Z Z35, Al /0r NM/Z M G. S. DUNN.

METHOD OF BBNDING METAL STRIPS EDGEWISE.

APPLICATION FILED NOV. 28,1906.

91 8,425. Patented Apr. 13, 1909.

6 SHEETS-SHEET 4.

Witnesses: Inventor @znwa/m/yz E1 0 5. Dunn,

ywwm/a awe -27 fi m G. S. DUNN.

METHOD OF BENDING METAL STRIPS EDGEWISE.

APPLICATION FILED NOV. 28. 1906.

Patented Apr. 13, 1909.

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G. S. DUNN.

METHOD OF BENDING METAL STRIPS EDGBWISE.

APPLICATION FILED NOV. 2a, 1906.

918,425, Patented Apr. 13, 1909 6 SHEETS-SHEET n.

Witnessea= Inventor,

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#Ww 6. M 27 UNITED sTAT s rATENT OFFICE.

GA-NO S DUNN, OF EAST- ORANGE, NEW JERSEY, ASSIGNOR TO CROCKER-WHEELER COMPANY,

OF AMPERE, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF BENDING METAL STRIPS EDGEWISE.

l No. 918,425.

Specification of Letters Patent. Original application filed November 16, 1905, Serial No. 287,721. Divided. and this application filed Noiiember Patented April 13, 1909.

28, 1906. Serial N0. 346,463.

To all whom it may concern:

Be it known that l, GANG S. DUNN, a citiz'en of the United States of America, and a resident of East Orange, county of Essex, and State of New Jersey, have invented certain new and useful Improvements in Methods of Bending Metal Strips Edgewise, of which the followin is a specification. My. invention relates to methods for coiling 'edgewi e thin copper strips, including as the most difficult type of coil those having c'onvolutions of elongatedform with straight sides joined by ms of circles, and other forms not truly circular.

The object of the inventionis to produce such coils in a convenient and economical manner accurate in its results.

My invention consists in certain methods pertaining to this art of winding flat strips ed et isean of which is completely described and illustrated herein, but it will facilitate "the understanding of the invention to state briefly some of its general characteristics. As a convenient means for pertornnn'g. these methods, I have illustrated a low-tension necessity of attaching an end of the strip to or of winding the strip about the mandre for the purpose of anchoring it, and no material tens-ion is applied to the strip as. it approaches the point of bending. The bending is effected by a pressure applied to the edges of the strip at three places, by "he mandrel and two shoes, the shoes pi ing against theouter edge and the mandrel. pressing against the inner edge at a point between the two shoes,

which hold the strip a'ainst 1 the l'oending pre'ssure. The shoes iavo contacts. as straight of 'e'dgiess the straightest part or the exter or boundinglme of the proposed coil it operates without the 5 0 elongated coils in position ust preceding and. the shoes are so mounted that the eontact edges are independently adjustable to the e'd'e oi the strip. The strip is pulled through the bending instrunientalities by a rotary friction-clamp.

' 4 When the machine is organized for windin" non-circular coils, the mandrel is built of re atively movable sections whereby the 'stri is overwouhd to correct for the springbut in the metal, so that the coil is in its final shape when it leaves the mandrel.

machine-has a no'n reciprocating rota'ry mandrel and 'a' two-shoe l ending de vice, and when organizedfor winding nonings', which form a part of this application,

Figure 1 is a plan view of a machine embodying my invention and constructed for the formation of elongated coils. Fig. 2 is an end elevation of the machine with the rotating parts in section on the line 11-11 of Fig. 4, and in position forbending over one of the curved ends. Fig. 3 is an end elevation of the machine with the rotating part at the mint in its revolution where the strip winds trom one of the curved ends on to one of the straight sides, and the two parts of the mam drel are shifted with res set to each other as compared with their re ation to each other in the preceding figure to allow for the overwind. Fig. 4 is a side elevation of the machine with the pressure lever bending saddle and forming mandrel in section on the line lV-IV of Fig. 2. Fig. 5 shows face views of the two parts of the forming mandrel. Fig. 6 is a front elevation of a forming mandrel and directly cooperating parts for less shift of the two parts to allow for the overwind, together with arrows which indicate the intensity and direction of the forces acting on the ports of the mandrel to cause it to shift. turning moments of these forces. referred to the point of pivoted support of one of the parts of the mandrel. Fig. 8 shows a. formmg mandrel and directly cooperatin parts for the formation of rectangular coi s with rounded corners. Fig. t shows my invention adapted to the formation of circular coils.

Briefly stated, the coiling apparatus comprises rotary mandrel which is revolved about a fixed a'xis and a. bendim saddle which is pressed toward one side of t e mandrel. The stri to be coiled is fed between the saddle an( the mandrel in a direction which must be about tangent to the surface of the latter at the point of entrance under the saddle. In case a non-circular mandrel is employed the saddle has a radial movement to and from the mandreha cis, and also a considerable rocking movement to preserve its alinement with, or substantially tangential relation to, the portion of the Fig. 7 is a strain diagram showing the dependent of each other.

the strip leads into the coiling apparatus along a line which is not only constantly varying in its distance from the axis of rotation of the mandrel, but which oscillates through a considerable angle. A portion of this movement will be apparent by comparing the directions r-a along which the strip passes to the coiling apparatus while this a paratus is in the positions illustrated m Figs. 2 and 3 respectively.- Thestrip is conveniently supplied from a reel R and it is necessary first to lead this strip to the shifting point a and in such manner that it will be permitted to take the proper tangential direction. To efiect this it is first bent flatwise and led around an are which is preferably about and slightly more than a right angle (but which may be'considerably less), and-then conducted to the bending apparatus. This turn in direction is defined by a guide L which is ivoted in the apparatus and has considerab e angular movement during the operation of the machine, as can be seen by com aring the positions of the end of the guide in Figs. 2 and 3; and the reel is preferably so located that the point y of deivery of the strip is about on a line with the a proximate center of the curved path of t e end of the guide. One result of this location is that the end of the guide throughout its extent of movement will remain at about the same distance from the point of delivery, and the strip between the reel and guide will notat any time be slackened by the angular movement of the guide. Another and more important result of the location-of the reel above indicated is avoidance of any tendency to edgewise bending by reason of the, shifting of the direction of entry of the strip under the bending saddle; this is, obviously, attainable in other ways. This guide, though im ortant, isnot essential, particularly wit 1 thin strips. The guide is made as short as possible to keep own the range of movement of its outer end, but it must be long enough to hold the strip as it approaches the machine out of the way of the spool which holds the formed coils.

The winding apparatus has a revoluble forming-mandrel which may be conveniently mounted on the face-plate of a lathe. It consists when used for non-circular coils of two parts A A which have'a slight movement with respect to each other. The parts taken together have a contour a proximately the same as that desired for tlie interior of the coils, and a face the width of which is slightly less than the thickness of the strip to be coiled. The forming mandrel has a single flange in two parts B B, each part being integral with one of the partsof the mandrel and supporting'the mandrel-part. This is im ortant as the machine is intended for I ness of the-strip. The two flange-parts and mandrel-parts taken together constitute what may be termed a single flanged forming mandrel. The strip of cop er to be coiled is laid with one edge against t 1e forming face of 'the mandrel and one side against the flange of the mandrel, and is snugly held by a pair of clamps C C between which is the strip of copper and the flange of the mandrel so that the sides of the strip are closely confined on the one side by one of the clamps and on the other side by the flange. The bending is eflected by a leading shoe D, a following shoe E, and the mandrel, in cooperation, and takes place where the strip is snugly confined on the sides between one of the clamps andthe flange. Both of the shoes are pivoted between the clamps, and have straight contacting faces whlch contact with the edge of the strip. The shoes are slightly thinner than the cop er strips so that they will not he clampe when the clamps are adjusted to confine the strip snugly. The strip is confined on its sides throughout the portion between the shoes (where the bending chiefly takes place), and also for a short distance in advance of the leading shoe and in the rear of the following shoe (where there is also some flow of metal or tendency to flow-from the bending). In order to avoid excessive friction and resistance to the passage of the strip only the area of flow of metal is so confined.

The clamps and shoes together constitute what may be termed a bending saddle. This saddle is held down against the edge of the copper strip by means of a weighted lever F, a pin f pro'ecting from the lever enters a hole situated about midway between the )ivotal points of the shoes so as to fairly equalize the ressure between the shoes. The adjustment is such that the leading shoe will not crush the strip down into contact with the mandrel at a point directly under it, but will effect the principal bending at a point between the eading shoe and the following shoe. In this way the bending is efl'ected with less severe pressure between the shoe and the edge of the strip than would be necessary t0 force the strip entirely down to the mandrel under the shoe, which, with thin strips, would result in upsetting the edge of the stri This pressure may be adjusted in the weig t applied to the lever, but it is usually preferable to have an excess of pressure and to holdthe shoe at a slightly greater distance from the mandrel" than the width of the strip, particularly at the curved parts of the mandrel. I effect thisby-a rollerd on the pin withthe leading the linear 'movement of the strip. This shoe, the roller resting on the edge ofthe flange of the mandrel. This edge is she. ed to .act asa-cam which holds the leading s oe at such .a distance from the mandrel when bendingrover the curved portions of the man- .drel that the strip will not .be forced entireliy '20 irom =being communicated to the straight portions and causing them to bow. In order to secure a uniform distribution of pressure against the sides of the strip where the bend-' 'irig takes place one of the clamps C is faced with a piece of sheet .metal 0 which is backed with a sheet of rubber, fiber or other elastic,

material r. I The distribution and adjustment of pressures above indicated results in coils wherein the turns are of substantially uniform width and thickness throughout.

The strip has a traveling anchorage to the mandrel by means of a rotary clamp .er pmch-wheel consisting of two circular flanges G H between which the strip and the flange of the mandrel pass immediately after emerging from between the clamps of the saddle. These flanges .are drawn together by bolts, and one of them is preferably faced with an annular sheet 1 backed with rubber, fiber .or other elastic material .to .distribaite the pressure more uniformly.

The pinch-wheel revolves on a pin i on the .end of a weightedlever by which it is held in engagement with the strip and flange. The friction between the strip :and the fiange of the mandrel on the one side and between the strip and the flange of the pinch-wheel on the other side holds the stri from slipping withtrespect to the mandrel and puts a sufficient tensile strain upon the strip to draw it under the saddle. Through this tensile strain the friction on the strip from passing under the parts which contact with the edge is overcome, and the friction from contact with the parts which confine the sides of the strip at the point of bending is "also overcome.

efi'ect of the latter friction be mitigated or It is necessary that the the combined resistance will exceed the tensile strength of the strip or the holding power of the pinch-wheel. The friction against the sides where the bending takes place may be analyzed into two components. F rst, there is friction arising from friction is only on the side of the strip which is against one of the clamps of the saddle. Opposed thereto on the opposite side is the flange of the mandrel which has a linear movement with the strip and neutralizes any tensile stress from the linear friction on the opposite side. Second, there is friction fronr the transverse movement otthe strip radially .to the mandrel in being brought down into contact. This 'triction is only on the side of the strip against the flange of the mandrel. Opposed thereto, on the opposite side is one of the clamps of the saddle .with respect to which the strip has very little transverse movement, and which about equalizes any resistance from the transverse friction on the opposite side.

i In bending a copper strip to a mandrel in the manner indicated, there is a springback or unwind amounting to from one .to three per cent. of the arc, and an enlargement of about half of one per cent, so that, to produce a semi-circular bond with a given interior diameter, the mandrel should is about half of one per cent. smaller, and the curvatures of the arcs should exceed the required arcs from one to three per cent, and in the examples illustrated should exceed a semi-circle by about one and onehalf degrees. It is manifestly impossil; le to join the ends of two such arcs with straight lines in a rigid plane structure. The difficulty is overcome by me by making the mandrel in two parts. Each part has an arc of one hundred and eighty-one and one-half degrees with straight sides tangent to the ends of the arcs in the example in which it is required to wind coils with each convolution consisting of two semi-circular arcs joined by straight sides. In the example in which it is required to wind coils having rectangular convolutions, the sides of which are joined by ninety degree arcs, each part of the mandrel has two arcs of about ninety -one degrees joined by a straight tangent line and with straight tangent sides at the other ends of the .arcs. both sets of examples the two parts of the mandrel are each supported from a pin p '1) which projects from the faceplate of the spindle and engages a hole in a projecting arm P of the one mandrel part and passes through a slot in the other mandrel part.

The two mandrel-parts are hinged to each other at the middle point 0 of the mandrel and have a slight relative movement equal to the overwind so that the adjoining straight sides of the two parts on either side of the mandrel can be brought into alinement. This movement or fio of the two parts is made at each half revo ution just in advance of the layin of the strip on the side, the parts of whidh are brought into alinement by I I p v the resultant action of several forces. In the 7 form illustrated in Fig. 6, the flop of the man drcl takes place hen in the course of a revolution it reaches about the position illustrated. 'T'he forces acting on the mandrel to cause it to flophre the eighted lever bearing on the saddle and acting at the point a and a drag K r. hich is a clamp applied to the flange of the mandrel and anchored through a link J at a fixed point The former force may be about two hundred pounds and the latter force about fifty-five pounds under the conditions shown; Advcrsely acting forces are the reaction of the pinch-heel u hich may be 'lifty pounds acting at b, and the reaction of the saddle ahich may be one hundred and fifty ounds acting at 1-. 'ihese forces act direct y upon the mandrelpart A through its flange B except the drag which acts on the mandrel part A concurrently a ith the action of the other forces on the part A, and indirectly through the pin connection on the mandrel part A, where, by reason of the three to one ratio of the lever arms 11 and z, the force of the drag is three times as much. The turning moments of these forces acting, on the mandrel part A to turn it about the pin 1) are the productsof the forces with their ever arms as indicated in Fig. 7, and the algebraic sum with the forces adjusted as indicated results in the required counter-clockise movement of the mandrelpart A about its pivot point p. The principal adversely acting turning moment is the reaction of the saddle, and to reduce-this as much as possible, its lever arm is shortened by locating the pivot point p above the line of symmetry of the mandrel part. \w ith the more elongated mandrel of Figs. 1 to 5, this lever arm is much shorter and this adverse turning moment is so much reduced that a drag is not, necessary.

The strip, after passing the pinch-wheel, meets the saddle and falls array from the face i of the mandrel, so that it does not interfere with the llop of the mandrel nor get in the u ay of the feeding-guide. 'lhe finished convolutions are received on a skeleton spool consisting ofparallcl prongs S S which are supported from the ends of the ins p p which extend from the face-plate of the spindle. This part of the apparatus is of inexpensive construction and may be used with different mandrels. Neither is it necessary tensions readily op osed by a pinch-wheel, is

that the strip is inc osed at the point of bending between a stationary wall and a flange which travels uith the mandrel and the strip, thereby helping it along.

it w: ill be clear that many changes may be made ithout departing from the spirit of my invention.

The apparatus herein set forth is claimed in United States Patent N 0. 839,060, granted December 18, 1906, upon m application filedNovember 16, 1905, Serial of which this'ap lication is a division.

Having now dhscribed my invention and the best way known to me of practicing it, What 1 claim and desire to secure by Letters Patent of the United States is:

1i 'lhe method of forming non-circular continuous coils from a metallic strip, which consists in coiling upon a mandrel successive convolutions, the material forming each convolution being bent throu h arcs the sum of which exceeds a circle an then released-before the succeeding coil is formed, substantially as described 2. The method of forming non-circular continuous coils from afiat metallic strip which consists in feeding the strip to a noncircular mandrel the axis of rotation of which is eccentric to the arcs of curvature, from a point out of the plane of rotation of the mandrel, bending the strip flat ise to bring it into said plane of rotation, and coiling it upon the mandrel edgeuise, substantially as described.

3. 1n the art of ainding fiat strips edgev-ise, the method which consists in confining the sides of the strip between faces of parts of the mechanism one of which travels with the strip, and applying pressure at three points lying along the edges of the strip two ying upon the outer edge and one lylngupon the inner edge and intermediate bet a een the other t. .o, substantially as described.

Signed by me at Ampere, Ne a Jersey, this 27th day of November, -1906,

' GANG S. DUNN.

Witnesses HENRY J. FULLER, HARVEY (3. HARRISON. 

